As a lens for obtaining an enlarged image of an observation object, a solid immersion lens (SIL) is known. The solid immersion lens is, for example, a microscopic lens which is formed in a semispherical shape or a super-semispherical shape called a Weierstrass sphere and has a size of about 1 mm to 5 mm. When the solid immersion lens is installed to contact a surface of an observation object, both a numerical aperture (NA) and a magnification are enlarged and thus an observation can be performed with high spatial resolution.
As a solid immersion lens holder that holds such a solid immersion lens at a front side (an observation object side) of an objective lens, for example, a solid immersion lens holder disclosed in Patent Literature 1 is known. The solid immersion lens holder disclosed in Patent Literature 1 has an accommodation space which is larger than a spherical face portion of the solid immersion lens and holds the solid immersion lens in a swingable manner. Accordingly, in a case where a bottom face (a contact face) of the solid immersion lens contacts the observation object, the solid immersion lens swings inside the solid immersion lens holder so that the contact face follows the observation object so as to closely contact it. As a result, the solid immersion lens and the observation object can satisfactorily closely contact each other.